The invention relates generally to electrical connectors, and, more particularly, to coaxial board-to-board connectors.
Coaxial connectors for interconnecting electrical components typically include a conductive signal path and a conductive shield surrounding the signal path. The conductive path through the shield provides a return path through the connector and also prevents radio frequency (RF) leakage from the signal path. Sometimes referred to as RF connectors, coaxial connectors are used with and are employed in a wide variety of electrical and electronic devices and packages.
Like other electrical connectors and components, the increasing miniaturization of modem devices has rendered known coaxial connectors unsuitable for use in smaller and smaller devices and electronic packages. For instance, cellular phones and other hand-held or portable devices are becoming smaller in physical size, while offering a host of expanded features and capabilities. Consequently, internal electronics which make the desired features possible must be crowded into smaller and smaller spaces which are incapable of accommodating known connectors. This problem is especially acute for board-to-board connectors that interconnect circuit boards within the constrained internal space of the device.
One known board-to-board coaxial connector that has been employed in Europe is available from Tyco Electronics as part number 619193. The connector includes a center contact assembly and a shield assembly surrounding the center contact assembly. The center contact assembly includes a two-piece conductive housing mounted to a first circuit board on a lower end, and a spring-loaded plunger contact reciprocally mounted in the housing and extending from an upper end. A ball bearing is employed between an end of the spring and the plunger contact to offset the spring load to the plunger contact within the housing.
The shield of part number 619193 includes a lower contact ring base which is fixedly coupled to a first circuit board, and an upper spring loaded member reciprocally movable within the base and including six longitudinally extending contact beams separated by slots for producing desired impedance and RF characteristics of the connector. The lower end of the center contact assembly housing and the lower contact ring of the shield are fixedly mounted to a first circuit board, and when a second circuit board is brought into contact with the connector, the plunger contact and the upper member of the shield are depressed against the bias of the respective springs, thereby providing a normal contact force against the second circuit board. A signal path and a return path are therefore established between the first and second circuit boards through the center contact assembly and the shield assembly. This construction is disadvantaged, however, in several aspects.
For example, the construction of the coaxial connector of part number 619193 includes at least nine different parts that must be assembled to produce the connector. The connector may therefore be prohibitively expensive for some applications. In a high volume business of producing such connectors, each component adds an incremental cost to the connector that, over a large number of connectors, can be substantial. If the number of components can be reduced and if manufacture of the connector can be simplified, manufacturing efficiency will be improved and cost savings may be realized.
Additionally, the coaxial connector of part number 619193 may accommodate a minimum board-to-board separation of about 6.65 mm and about a two degree misalignment of the first and second boards, thereby rendering the connector unusable for board-to-board clearances below the 6.65 mm threshold and unreliable when a misalignment of the boards is greater than two degrees.
Still further, as the size of the circuit boards is reduced, the space occupied by the connector on a circuit board, sometimes referred to as a xe2x80x9cfootprintxe2x80x9d of the connector, is an important consideration. Reducing the space occupied by a connector can free up valuable board space for other circuit components.
According to one exemplary embodiment, a low profile electrical connector comprises a center contact assembly comprising an integral housing and a spring loaded plunger contact therein and a shield assembly coaxial with the center contact assembly. The shield assembly comprises a slotted shield base adapted to be coupled stationary to a circuit board, and a contact ring is reciprocally mounted to the shield base for relative movement thereto.
According to another exemplary embodiment, a low profile coaxial electrical connector comprises a substantially cylindrical center contact assembly comprising an integral conductive housing, a contact plunger reciprocally mounted within the housing, and a first spring. The first spring biases the plunger contact to an extended position relative to the housing, and the plunger contact is depressible against a bias of the first spring to a retracted position. A substantially cylindrical shield assembly is provided coaxial with the center contact assembly, and the shield assembly comprises a slotted shield base having an outer surface and adapted to be fixedly coupled to a circuit board. A contact ring is reciprocally mounted to the shield base and movable thereto, and a second spring biases the contact ring to an extended position relative to the shield base. The contact ring is depressible against a bias of the second spring to a retracted position, wherein the plunger contact and the contact ring are depressed to produce an overall height of the connector of about 4 mm when the plunger contact and the slotted member are in the retracted position.
According to another exemplary embodiment, a low profile coaxial electrical connector comprises a substantially cylindrical center contact assembly comprising an integral conductive housing, a contact plunger reciprocally mounted within the housing, and a first spring. The first spring biases the plunger contact to an extended position relative to the housing, and the plunger contact is depressible against a bias of the first spring to a retracted position. A substantially cylindrical shield assembly is provided coaxial with the center contact assembly, and the shield assembly comprises a slotted shield base having an outer surface and adapted to be fixedly coupled to a circuit board. A contact ring is reciprocally mounted to the shield base and is movable thereto, and a second spring biases the contact ring to an extended position relative to the shield base. The contact ring is depressible against a bias of the second spring to a retracted position, wherein the center contact assembly and the shield assembly are adapted to accept a board-to-board misalignment of about 3 degrees between a first circuit board and second circuit board.
According to another exemplary embodiment, an electronic package is provided. The package comprises a first circuit board and a second board having a separation therebetween and a shield assembly mounted stationary to the fist circuit board. The shield assembly comprises a slotted shield base coupled stationary to the first circuit board, and a contact ring reciprocally mounted to the shield base for relative movement thereto from an extended position relative to the first circuit board to a retracted position when contacted by the second circuit board. A center contact assembly is coaxial with and internal to the shield assembly, and the center contact assembly comprises an integral housing mounted stationary to the first circuit board and a spring loaded plunger contact reciprocally coupled to the housing and movable between an extended position and a retracted position relative to the housing. The plunger contact is depressed by the second circuit board to establish electrical connection therewith.